Requirements-Driven Requirements Driven Software D

Ó1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--1RequirementsRequirements--DrivenDrivenSoftwareDevelopmentSoftwareDevelopmentJohnJohnMylopoulosMylopoulosUniversityofTorontoUniversityofTorontoCatholicUniversityofCatholicUniversityofLouvainLouvain,,October26,1999October26,1999Ó1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--2AbstractAbstractSoftwareDevelopmenthastraditionallybeenimplementation-driveninthesensethattheprogrammingparadigmoftheday(structuredprogramming,object-orientedprogramming)dictatedthedesignandrequirementsanalysistechniqueswidelyused(structuredanalysisanddesign,object-orientedanalysisanddesignrespectively).Wespeculateonwhatasoftwaredevelopmentmethodologymightlooklikeifitwasfoundedonearlyrequirementsanalysisconceptsandtechniques.Forourpurposes,weadopti*[Yu94]asmodelingframework.i*supportsconceptssuchasthoseofactor,agent,positionandrole,alsoresource,taskandgoaldependenciesamongactors.Thepresentationsuggestselementsoflaterequirementsanalysis,architecturalanddetaileddesignthroughexamples,andnotesanumberofareaswheresuchamethodologymightbreaknewgroundwithrespecttotraditionalsoftwaredevelopmenttechniques,aswellasagent-orientedprogramming.Ó1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--3SoftwareDevelopmentTechniquesSoftwareDevelopmentTechniquesnSoftwaredevelopmenttechniquesofferconcepts,toolsandmethodsforbuildingsoftwaresystems.nTraditionally,suchtechniqueshavebeenimplementation-driven.nThismeansthattheprogrammingparadigmofthedaydictatedthedesignandrequirementsparadigms.nSo,structuredprogrammingledtostructureddesignandstructured(requirements)analysis,whileobject-orientedprogrammingledtoobject-orienteddesignandanalysis.nAligningtheparadigmsusedforrequirements,designandimplementationmakesperfectsense.Butwhystartwithanimplementationparadigm?WhatwouldWhatwouldrequirementsrequirements--drivendrivensoftwaredevelopmentlooklike??softwaredevelopmentlooklike??Ó1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--4EarlyEarlyvsvsLateRequirementsLateRequirementsnWeneedtodistinguishbetweenearlyphasesofrequirementsanalysis,whentheanalystistryingtounderstandanorganizationalsetting,fromlatephaseswhentheanalystformulatesasolutionOrganizationOrganizationSystemSystemOrganizationalmodelContractualrequirementsRequirementsRequirementsÓ1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--5EarlyEarlyvsvsLateRequirementsLateRequirementsnEarlyrequirementsamounttothedefinitionofasearchspace(“scoping”)andasearchamongalternativeswithinthatspace.nLaterequirementsamounttorefining,disambiguatingandcompletingthedescriptionofthechosenalternative.nnStructuredStructuredandobjectobject--orientedanalysesorientedanalysesareOKforlaterequirements.nnGoalGoal--orientedanalysisorientedanalysisismoreappropriateforearlyrequirementsanalysisbecauseitfocusesonthedefinitionandexplorationofaspaceofalternativesÓ1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--6GoalGoal--OrientedAnalysisOrientedAnalysisnGoal-orientedanalysisfocusesonearlyrequirementsphases,whenalternativesarebeingexploredandevaluated.nDuringgoal-orientedanalysis,westartwithinitialgoalssuchas“Higherprofits”,“Fastertime-to-market”,“Schedulemeeting”,“Easilymaintainablesystem”,“Goodperformance”etc.andkeepdecomposingthemuntilwehavereducedthemtoalternativecollectionsofdesigndecisionseachofwhichcansatisfytheinitialgoals.nInitialgoalsmaybeorganization-orsystem-oriented;theymayalsobeconflicting,sotheanalysismustfacilitatethediscoveryoftradeoffsandthesearchofthefullspaceofalternatives,ratherthanasubset.Ó1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--7GoalGoal--OrientedAnalysisisnotNew!OrientedAnalysisisnotNew!nSpecificationofcompositesystems--[Feather87]nGoal-orientedelaborationofrequirements--ALBERT[Dubois94]nGoal-orientedrequirementsacquisition--KAOS[Dardenne93]nKnowledgerepresentationandreasoninginthedesignofcompositesystems--Critter[Fickas92]nGoal-orientedrequirementsanalysis--Potts,Antonni*andNon-FunctionalRequirementsframework--Yu,ChungnNATURE--[Jarke93]nF3--[Bubenko93]...andmanyothers...Ó1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--8Thei*FrameworkThei*FrameworkCustomerInsuranceCompanyCarrepairedCustomerhappySettleclaimMaximizeprofitsGoalsarerelative,fulfillmentiscollaborativeGoalsarerelative,fulfillmentiscollaborativeÓ1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--9MeansMeans--EndsAnalysisEndsAnalysisSettleclaimVerifypolicyClaimsHandlingClaimsClaimsHandlingHandlingHandleclaimSettlementcost?PrepareofferWhosefault?GetaccidentinfoDeterminefaultPoliceWitnessDoctorAppraiserDeterminecosttosettleAccidentinfoSufficienttreatmentInjuryinfoAppraisedamageMinimalrepairsDDDDDActorActorboundaryboundaryInsuranceCompanyÓ1999JohnMylopoulosRequirements-DrivenSoftwareDevelopment--10StrategicDependencyModelsStrategicDependencyModelsBodyShopOwnerAppraiserInsuranceCompanyCarrepairedPayrepairsMaximizeestimateContinuebusinessDDDDDDDDDDDDDDDDDDClaimspayoutPremiumpaymentDDCustomerhappyRepairscoveredDDAppraisedamagesMinimizerepairs